Wondering what tools are available to remotely edit (find and replace actually) the PATH environment variable on all users workstations across the enterprise? We do use SCCM (formerly SMS), but I don't know if that provides the capability to do that. Is this possible with Powershell maybe?

You could run that as an Active Directory Startup Script on the affected computers. You could even get fancy and put some kind of flag in the registry (join the computer to a group that's denied rights to apply the GPO again, etc) to make the script only run once per computer.